* wxFrameLayout should compile in unicode builds for ports other than wxMSW or wxGTK...

* wxFrameLayout should compile in unicode builds for ports other than wxMSW or wxGTK too - fix missing _().
* wxMac has Reparent, so use it in wxFL instead of the, now unicode-compilable, warning messagebox.
* Code cleanup.
- Probably some more ports have Reparent too, so could add into the CPP check. And it might be a good idea to do for
the non-supported ports what wxGTK1 does (just return, not spew a messagebox). If Reparent already does nothing for
unsupported ports, then could get rid of the CPP logic completely.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@37480 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775